An arcjet thruster provides a thrust to a spacecraft by heating a gas with an electric arc and expanding the heated gas through a nozzle. Over a practical operating range, the arc has a negative resistance characteristic, i.e., arc voltage decreases with increasing arc current, and is thus inherently unstable. A typical power supply for an arcjet thruster employs a pulse width modulated (PWM) converter operating in a current-controlled mode. Disadvantageously, however, operation of such converters involves hard, i.e., lossy, switching, such that operating frequencies are relatively low (e.g., 20 kHz), thus necessitating the use of relatively large and heavy magnetic and capacitive components.
Accordingly, it is desirable to provide an efficient and lightweight power supply for an arcjet thruster.